Materials transport container

ABSTRACT

A materials transport container having a floor and two opposed upwardly extending side walls and a front wall. The container is supported to enable tilting for unloading of material from a rear end. The container has a substantially continuous and smooth hard faced surface on a rear portion of the floor adjacent the rear end to enhance sliding of its load over the smooth hard faced surface. Additionally arcuate surfaces bridging a junction between one or more of the front and side walls and the floor of the container to reduce hangup of material. The arcuate surfaces are smooth hard faced surfaces. The hard faced surfaces are provided by removable wear plates with gaps between then to allow flexion and ease of removal. It is found with use these hard faced wear plates become polished and greatly assist with the removal of material from the transport container.

FIELD OF THE INVENTION

The present invention relates to bulk materials transport containers,and in particular to bulk materials transport containers such as dumpbodies of dump trucks or buckets of front end loaders that have improvedflow characteristics of bulk materials across surfaces of the containerupon unloading the container.

BACKGROUND OF THE INVENTION

Bulk materials transport containers such as dump bodies on dump trucks,buckets on front end loaders and the like are used in many industriesfor the transport of materials from one area to another. For example, inthe mining industry dump trucks are used to transport mined materialsfrom the mine site to a processing site. In the case of the miningindustry, as well as many other industries, the material transported canhave a hardness that is greater than the material from which thecontainer is formed, which is typically steel. As a result, the loadmaterials can be very abrasive and movement of the materials acrossinternal surfaces of the container during loading, and more particularlyunloading, tends to wear the surfaces rapidly. Because of this thetransport containers can experience significant down time whilst thesurfaces are being refabricated to prolong the life of the container.

Movement of the materials across internal surfaces of the transportcontainer, such as when the container is tipped to allow flow out of anend of the container, leads to abrasion or scoring of the metal of thecontainer. Abrasion of the surface then results in an increasedresistance to flow of material across the surface and therefore aresultant increase in difficulty in emptying the container.

In practice, it is known that once an area of the container has becomeabraded there can be a significant ‘hang up’ of material in the abradedarea, which means that, despite the container being tilted or tipped toenable emptying of the material by gravity flow, some material does notflow out of the container under the influence of gravity alone. Forexample, referring to a dump body on the back of a dump truck, it hasbeen known for the forward most area of the container adjacent thejunction between the forward wall and floor of the container to becomeabraded so that when the container is tilted and the forward most areaof the container is raised, the material can be hung up in that area andwill not flow out of the container under the influence of gravity alone.Under these circumstances operators will normally rapidly raise andlower the dump body about its pivot in an attempt to jar the materialloose. This procedure then leads to an accelerated wearing of the dumpbodies as well as the hydraulic mechanism used to raise the dump body.Alternatively, some physical intervention is usually required to movethe load out of the container, which then raises issues of additionaltime and danger in emptying the container.

To overcome these difficulties it is known to hang lines of heavy metalchains across the dump body so that as the body is emptied, the chainsbang against the body and/or the material being emptied to therebyphysically prevent material being hung up in the body.

In many materials transport containers it is known to provide wearplates on surfaces that are subject to constant abrasion. For exampleU.S. Pat. No. 6,076,693 to Reiter et al. describes a sacrificial onepiece insert for a transport container such as a dump truck body. Theliner is formed from a plastics material and can be interchanged whenworn. Whilst the plastics liners may be useful for soft material such asflour, the hardness of material transported in the mining industry forexample means that the liners wear rapidly and for that reason are notsuited to many industries.

U.S. Pat. No. 6,007,132 to Burg et al. describes a liner suitable foruse in the dump body of a dump truck. The liner has raised strips of anabrasion resistant cladding wherein the raised strips are alignedtransverse to the flow of material so that the strips cause material totumble rather than slide over the surface. This tumbling action is saidto be less abrasive than a sliding action over the surface. However theraised strips protrude into the flow path of material and therefore aresubjected to strong abrasive forces and therefore tend to wear fasterthan if the material was sliding over the surface.

U.S. Pat. No. 6,022,068 to D'Amico relates to a modified dump truck bodywith enhanced hardness and thickness toward the rear of the body.D'Amico also does not disclose the use of removable wear plates or theprovision of an arcuate surface to assist in unloading.

U.S. Pat. No 6,174,014 to Hook et al., discloses the use of a liner foruse in the rear of a dump truck body. The liner however is a web ofprotrusions and does not disclose a smooth surface, nor the provision ofan arcuate surface between the floor and side or front walls of the dumptruck.

In many instances the prior art addresses issues of minimising wear, butnot of maximising the flow of material over a surface, and in particularover the surface of a dump body of a dump truck.

OBJECT OF THE INVENTION

The object of this invention is to provide a materials transportcontainer such as the dump body of a dump truck or the bucket of a frontend loader that obviates or alleviates any one of the above problems, orat least to provide the public with a useful choice.

SUMMARY OF THE INVENTION

In a first aspect, but not necessarily the broadest or only aspect, theinvention could be said to reside in a materials transport containerhaving a floor and two opposed side walls and a front wall said wallsextending upwardly from the floor, the container further having anunloading end (or rear end), the container supported to enable tiltingfor unloading of material from the unloading end, the container having asubstantially continuous and smooth hard faced surface on an unloadingportion of the floor adjacent the rear end, so as to enhance the slidingof material over the smooth hard faced surface, the hard facing isprovided by a layer of hard surfacing alloy there being provided one ormore arcuate surfaces bridging a junction between one or more of thefront and side walls and the floor of the container to reduce hangup ofmaterial thereon.

The container may be any suitable container for use in the mining,earthmoving, building or other industries in which material is requiredto slide over a surface during a loading or unloading operation.Examples include, but are not limited to, dump bodies for dump trucks,materials handling chutes, and buckets. For the purposes of illustrationthe invention will be discussed in terms of a dump body used on a dumptruck, wherein a forward end of the body is tilted upward to empty thematerial out of the back end of the body under the influence of gravity.A benefit of the present invention is that the decreased resistance tomaterials sliding over the surface means that the dump body does nothave to be rapidly raised and lowered, thus reducing wear on thehydraulic mechanism used to raise the dump body.

The hard facing may form an integral part of the body of the container,so that the container needs to be rebuilt should the hard facing beworn, however preferably wear plates are fitted to an already formedcontainer, so that the wear plates can simply be fitted to the body, andwhen worn can be taken off and replaced.

In addition to the above, in practice it is found that the junctionsbetween the side walls and the floor surface of dump bodies are alsosubjected to a high degree of abrasion and form an area where twoadhesive surfaces are angled to each other in such a way that materialtends to hang up in the junctions when the body is tilted, and thematerial does not flow under the influence of gravity alone.

Therefore in order to further assist flow of material and/or minimisehang up of material, plates may be fitted over junctions between one ormore walls and the floor surface so that the plates extend between thewall and the floor in order to minimise hang up caused by the angledjunction. The plates need not be in the form of wear plates and could beformed from mild steel, for example, provided that a combination of theplates over the wall/floor junction(s) as well as the wear plates on thefloor surface assists in flow of loaded material out of the container.

However, in one preferred form the materials transport container isprovided with one or more wear resistant plates extending between thefloor and wall of a container such that the plate extends over ajunction between the floor and a wall of the container.

In one particularly preferred form of this aspect of the invention theplates are curved and are fitted between the wall and the floor so thatthey are outwardly concave. Preferably the radius of curvature of theplates is such that the material is able to slide over the surfacewithout materials being hung up in an angled junction between the floorand wall.

It is found that the junction between the front wall of the dump bodyand the floor surface, as well as junctions between the side walls andthe floor surface tend to be abraded rapidly and therefore preferablywear resistant plates are fitted at least over one of those junctionsand more preferably over all wall/floor junctions. Most preferably thecontainer is fitted with wear resistant plates over the front wall andfloor junction, the side walls and floor junctions as well as on theback third of the floor surface.

The term wear plate is used herein to define any plate of materialhaving a backing and which has been hard faced with a suitable hardsurfacing alloy. It is the hard faced surface of the wear plate whichcontacts the material load and over which the material slides duringunloading.

In a preferred form of the invention, the wear plates are formed from amild steel backing onto which the hard surfacing alloy material isoverlayed. Preferably the hard surfacing alloy is a carbide containingalloy with a high carbide structure that has increased wear resistance.The carbides are preferably a combination of primary and secondarycarbides dispersed in an alloy matrix. The carbide particles themselvesmay have a Brinell hardness of 1600 to 1800. Preferably the combinedprimary and secondary carbide content of the alloy is greater than 30%and more preferably is greater than 40%. The hard surfacing alloy may beany suitable alloy however preferably the alloy is a carbide containingalloy, such as chromium carbide, niobium (columbium) carbide, tungstencarbide, vanadium carbide, cobalt carbide or any other suitable alloythat can form suitable carbides.

Preferably the hard surfacing alloy has a hardness that is greater thanthe hardness of the material from which the container is formed. Morepreferably the hard surfacing alloy has a Brinell hardness of greaterthan 500 and the wear plates are fitted to a steel container having aBrinell hardness of less than 350.

It has been found that the wear plates formed from these materials tendto become highly polished upon sliding of material over the surface andthat the polished surface significantly decreases any adhesive contactbetween the surface and the materials, especially moist materials.Therefore the wear plates not only minimise scoring of the surface butalso become highly polished as they are used which therefore decreasesresistance to sliding of materials over the surface on use.

In practice it is found that a rear portion of the floor surface of thedump body experiences significant abrasion and once it is abraded itlimits flow of material out of the container because the abraded surfaceis the lowermost surface when the container is tilted for unloading. Theabraded or scored lowermost surface then tends to cause the load ofmaterial to bridge, stick, freeze or hang up on the lowermost floorsurface, therefore resulting in the load being hung up in the dump body.

Preferably the wear plates are provided in strip form so that thesurface to be covered can be covered by a plurality of strips. Thestrips may be abutted against one another to form a more or lesscontinuous surface. This allows surfaces of various sizes andconfigurations to be covered without having to manufacture plates toconform to any specific size or shape. More preferably however, thestrips are laid transverse to the direction of flow of material and theyare laid with a gap between adjacent strips, to allow for flexion ofadjacently placed wear plates. The width of the gap may be between 5 and20 percent of the width of the strips used. For example, for strips thatare between 200 and 400 mm wide, a gap of between 25 and 30 mm ispreferably left between adjacent strips. Preferably, the gap may be morenarrow so that when loaded material fills the gaps it does notsignificantly affect sliding of the material over the hard facedsurface.

In one form of the invention, the whole floor surface of the dump bodyis covered with wear resistant plates, although it will be appreciatedthat this may not be necessary as it has been found that for most loadmaterials coverage of about the back third of the container issufficient.

Alternatively, or in addition, one or more walls of the container, orsections thereof, may also be covered by the wear resistant plates.

The transport container may be manufactured with the wear plates fittedor alternatively an existing container may be modified by fitting wearplates to existing surfaces of the container.

In a second aspect the invention could be said to reside in a vehiclehaving a materials transport container of the first aspect of theinvention.

In a third aspect the invention could be said to reside in method ofminimising hang up of material in a materials transport container of thetype that can be tilted to one side or to the back for unloading, themethod including the step of fixing wear resistant plates according tothe first aspect of the invention.

The plates may be fixed using any suitable means, including by use ofstuds or other fasteners, by welding in countersunk hole inserts, and byplug or stitch welding.

In a fourth aspect, the invention could be said to reside in a materialstransport container having at least one surface over which materialslides for unloading of the container and having a first and secondopposed wall extending upwardly on either side of the container, and oneor more wear plates covering at least a part of said surface, said wearplate(s) reducing abrasion or scoring of the surface so that resistanceto sliding of materials over the surface is reduced and said plates laidin strips transverse to the direction of flow of material over thesurface with gaps formed between adjacent strips, there being providedone or more arcu ate wear plates bridging a junction between the sidewalls and the floor of the container to reduce hangup of materialthereon.

This form of the invention is not necessarily restricted to the materialtransport containers of the type described in the previous aspects ofthe invention, and as such this form of the invention can includematerials handling chutes, and like equipment.

The surface to be covered can be covered by a plurality of strips andthis allows surfaces of various sizes and configurations to be coveredwithout having to manufacture plates to conform to any specific size orshape.

The plates may be fixed using any suitable means, including by use ofstuds or other fasteners, by welding in countersunk hole inserts, and byplug or stitch welding.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding the invention will now be described withreference to an illustrated embodiment. The drawings describe anillustrated embodiment wherein,

FIG. 1 is a side view of a dump truck having a dump body of the presentinvention,

FIG. 2 is a side view of a dump body with the locations of wearresistant plates shown in phantom,

FIG. 3 is a plan view from above of a prior art dump body showing commonareas for hang up of material,

FIG. 4 is a plan view from above of a dump body according to the firstand second aspects of the present invention,

FIG. 5 is a cross sectional view through a wear resistant plate for usewith the present invention,

FIG. 6 is a perspective view of a further form of dump body havingwall/floor junction and floor surface wear plates,

FIG. 7 is a side cross sectional view showing a wear plate fitted over aside wall/floor junction, and

FIG. 8 is a longitudinal side view showing spacing between sidewall/floor junction wear plates.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT

Similar reference characters indicate corresponding parts throughout theseveral views of the drawings.

Dimensions of certain of the parts shown in the drawings may have beenmodified and/or exaggerated for the purposes of clarity or illustration.

FIGS. 1 to 4 show a dump truck carrying a dump body into which materialcan be loaded for transport and then unloaded. Dump trucks of this typeare typically used in the mining and construction industries andtherefore the material to be transported can include soil, rocks, coaland the like.

The dump truck (10) is a self propelled vehicle and may be anoff-highway vehicle that is used to carry tons of material in operationssuch as mining. Dump truck (10) includes a chassis (12) that issupported by wheels and tyres (14). The chassis (12) carries a cab (16)at a forward end and a box-like rigid load carrying dump body (18) atthe back end. Whilst the illustrated embodiment shows a self propelledvehicle, the container of the present invention may also be in the formof a trailer or any other suitable form.

The dump body (18) is pivotally coupled to the chassis at the back endand the dump body can be tilted between a loading position and anunloading position (shown in phantom in FIG. 1) in which the forward endof the dump body is raised to allow material to flow out of the back ofthe body under the influence of gravity. The forward end can be raisedusing any conventional mechanical or hydraulic lifting mechanism knownin the art.

The body (18) has a substantially rigid planar floor (20) and a pair ofrigid, spaced side walls (22) extending upwards from the floor. A rigidfront wall (24) also extends upwardly from the floor (20) and isconnected to each side wall (22). The floor and walls form a generallybox shaped materials container for carrying a payload. An open rearwardspillway (26) allows for dumping of the material out of the back of thebody. The side walls, front wall and floor are formed of steel plate.

In an unmodified form, a back third or so of the floor is prone toabrasion by the flow of material over the surface. In practice it hasbeen found that about 90% of the wear occurs in the back 0.5 to 1 meterof the floor surface. Abrasion of the surface then provides keyholds forthe load to attach to, thus retarding the flow of material over thefloor surface. In practice this has as significant impact on impedingthe load from sliding off the surface. The present invention provides acontainer having one or more wear plates (27) covering preferably atleast a back third of the floor surface (20) and/or one or more wearplates (34) extending between a wall and the adjacent floor surface. Thewear plate(s) reduce abrasion or scoring of the surface so thatresistance to sliding of materials out of the container is reduced. Thisthen leads to a benefit in that in unloading a dump body it is notnecessary to rapidly raise and lower the dump body to ensure that thematerial slides over the surface and reduces wear on the hydraulics usedin lifting the dump body.

Under normal conditions of use, the material carried in the dump bodymay contain a considerable amount of moisture. On being dumped into thebody and then transported the moist material can become compacted andthe combination of the moisture content and the compaction creates highadhesion forces within the material load. This then leads todifficulties in emptying the material from the container because theentire load wants to be emptied at the same time.

As best seen in FIGS. 2 and 4, the wear plates cover approximately theback third of the floor surface of the container. The wear plates are inthe form of strips of hard surfacing alloy (30) coated onto a mild steelbacking (32). Wear plates that are particularly suited to this purposemay be manufactured according to the weld cast method described U.S.Pat. No. 5,362,937. These plates comprise a homogeneous alloy that isoverlayed and smoothly bonded to a mild steel backing. The thickness ofthe alloy may be between 6 and 12 mm and the thickness of the mild steelbacking may be between 5 and 11 mm.

Alloys with up to about 7 to 12 percent carbon and 20 to 30 percentalloy (usually about equal parts of manganese and chrome with somenickel) are suitable for use with the present invention. In these alloyshard primary and secondary carbides are formed and dispersed throughoutthe wear surface and they are much harder than the surrounding matrixand thereby provide excellent abrasion resistance. For example carbideshaving a Brinell hardness of 1600 to 1800 may be formed in the alloy.This is compared to the steel plate from which the dump body is formedwhich typically has a hardness of 250 to 300 Brinell. When the carboncontent is less than about 3 percent the amount of carbides formed issmall relative to the matrix and these alloys exhibit good abrasive wearresistant while retaining toughness and are therefore resistant to acombination of abrasion and impact. As the carbon content increases (upto about 7 percent) in the carbide containing alloys, the abrasionresistance increase and the toughness decreases.

In practice it has been found that the wear plates with these hardsurfacing alloys tend to become very highly polished upon sliding ofmaterial over the surface and that the highly polished surface providesa poor adhesive contact between the surface and wet materials. Thereforethe wear plates not only minimises scoring of the surface but alsobecome polished which therefore decreases resistance to sliding ofmaterials over the surface on use. Therefore the present inventionprovides not only a surface which does not wear or become abraded asreadily, but also becomes polished upon use which therefore assists inunloading, even in the case of materials having a significant moisturecontent.

In trials conducted to date, a dump truck fitted with plates accordingto the present invention having an 8 mm alloy surface and a 10 mm mildsteel backing has been operated for 6000 hours and there is still nosignificant wear on the floor surface. By contrast, a similar truckfitted with prior art surfacing plates of 25 mm thickness gave about1000 hours of service before significant abrasion of the surface andhang up of materials was observed.

The upper surface of the wear plates is substantially flat in that itdoes not contain any protrusions, although it will be understood that acurved surface may be provided for that allows sliding of materialthereon. This is in contrast to some prior art wear plates which havehemispherical wear protrusions, or raised strips extending across thesurface.

Preferably the alloy of the contacting surface of the wear resistantplates has a hardness of greater than 500 Brinell hardness. The steelplate from which dump bodies are formed is typically 250 to 300 Brinellhardness.

The plates are fixed to the flow surface using any suitable means,including welding, by use of studs, by welding in countersunk holeinserts, by plug welding and by stitch welding.

The wear plates are provided in strip form of between 100 and 500 mmwidth. Most preferably the strips are 300 mm in width. A wear resistantsurface can be built up on the floor surface by abutting strips againstone another to form a more or less continuous surface. The ends of thestrips are cut at an angle of 45° and adjacent strips can be abuttedendwise and lengthwise. In this way surfaces of various sizes andconfigurations can be covered without having to manufacture plates toconform to a specific size or shape.

The strips are preferably laid transverse to the flow direction ofmaterial, although they may also be laid parallel to the flow directionof material in some circumstances.

In the illustrated embodiments and in a preferred forms of theinvention, the strips are not abutted against one another but a gap (33)is left between adjacent strips. The gap provides several advantages.Firstly, when wear plates are fitted to form a more or less continuoussurface it is often found that the wear plates crack and fall outbecause the plates themselves lack the degree of flexibility of thesheet metal of the dump body. The provision of gaps between adjacentstrips allows the sheet metal of the dump body to flex and the wearplates can move together and apart to accommodate the flexion withoutcracking and falling off of the surface. Another advantage of providinggaps between adjacent plates is that individual plates are readilyremoved and replaced. Thus if one particular area becomes worn it mayonly be necessary to replace some of the wear plates. Individual wearplates may be fixed to the surface by stitch welding.

The width of the gaps is such that when loaded material is caught in thegaps it does not substantially affect passage of material over thesurface. To achieve this it is found that the width of gaps may be lessthan about 20% of the width of the strips. Alternatively, at least 80%of the surface that is hard faced must be wear resistant plate. In useit is found that gaps with a width of between 5 and 20% of the width ofthe strips are sufficient to allow flexibility of the hard facedsurface, but also to not substantially affect passage of material overthe surface. Once the width of the gaps is any larger than about 20% thegaps tend to act as ‘rockboxes’ that fill with the loaded material. Thismay be satisfactory for dry materials because the rockboxes form abarrier between the loaded material and the floor surface. However ifthe loaded material contains any moisture, such as may be the case inmining operations, the material is prone to stick together and thereforethe larger width gaps may affect passage of material over the surface assome of the material becomes trapped in the gaps.

Coverage of the back third of the container floor with wear resistantplates may be considered a preferred minimum coverage (although coverageof the most wear prone 0.5 to 1 meters will provide for certainadvantages) and the wear resistant plates may cover the whole floorsurface. However it will be appreciated that the fitting cost willtherefore rise accordingly and a benefit of the present invention isthat only about the back third need be covered in order to minimise hangup of material in the body.

In practice it is found that the back third of the container experiencessignificant abrasion and once it is abraded it limits flow of materialout of the container because the abraded surface is the lowermostsurface when the container is tilted for emptying. In particular it hasbeen found that around 90% of the wear occurs in the lowermost 0.5 to 1meter and therefore it is expected a significant reduction in the amountof hang up will also be observed if less than the lowermost third iscovered by wear plates. The provision of wear resistant plates at thispoint therefore minimises any tendency for the material to not slideover the surface. Thus, the easy and rapid flow of material across thelower third of the floor surface then means that the lower part of thematerial flows off easily and thence the upper material flows directlybehind it.

Any one or more of the side walls or front wall, or sections thereof,may also be covered by the wear resistant plates. In this way anyabrasive resistance to flow exerted by the walls may also be minimised.For reasons discussed previously, it may only be necessary for the backthird of the side walls to be covered by wear resistant plates.

In practice it is also found that the angular nature of the junctionbetween the side and front walls and the floor surface also provideskeyholds for the material to latch to. Thus for instance it is knownthat in an unmodified dump body when the body is tilted a certainquantity of material remains attached to the uppermost portion of thetilted body and does not slide down under the influence of gravity.Additionally, the junctions between side walls and the floor surfacecause material to hang up in those regions of the dump body.

Plates may be fitted at the junctions between the side walls and thefloor and the front wall and the floor to minimise hang up of materialin those regions. The plates need not necessarily be formed from wearresistant material and for example mild steel could be used to reducecosts. The effect of these plates removing the angular wall/floorjunction in addition to the effect of the wear resistant plates on theback third of the floor surface may be sufficient to minimise hang up inthe dump body. However in that case the wall/floor junction plates willbe come abraded and worn over time. For that reason it is greatlypreferred that the wall/floor junctions are also fitted with wearresistant plates (34) which are fitted over a junction between walls andthe floor of the body. A combination of the angle of the wear resistantplates and the flow characteristics of the surface thereby minimise thehang up of material in the areas where the plates are fitted.

In one form of the invention that is illustrated in FIGS. 1 to 4, wearresistant plates are fitted over the junction of the front wall and thefloor, as well as to the back third of the floor surface. The plates(34) are curved and are fitted between the front wall and the floor sothat they are outwardly concave. The plates are welded to each of thefloor and wall surfaces and a gap is provided between the ends ofadjacent plates. It is found that a wear resistant plate (34) having aradius of curvature of at least 250 mm is suitable for this purpose.Preferably the radius of curvature is 250 to 500 mm, and most preferablyis 300 mm.

In the embodiment illustrated in FIGS. 6 to 8, curved wear resistantplates (34) are also fitted along the junction between side walls andthe floor. In this case the plates are formed from strips of the samewidth as those used on the lower third of the floor surface and thestrips are fitted with gaps between adjacent strips, as best seen inFIG. 8. The strips are 300 mm wide and the gaps are 25 mm wide. Thestrips are fitted so that they are transverse to the direction of flowof material out of the dump body.

As best seen in FIG. 7, many existing dump bodies have an approximately45° angled wall (36) at the junction between the side walls and thefloor surface. It is found that in that case the angled junctionsbetween walls (36) and the floor or side wall still cause material tohang up in the area. However fitting of a curved wear resistant platehelps to ameliorate this problem.

As best seen in FIG. 7, the curved wear plates are fitted over the sidewall/floor junction so that an apex of the curve bears against theangled side wall (36), thereby distributing some of the load borne bythe wear plate back to the dump body. For the side wall/floor junctionit is found that a wear resistant plate (34) having a radius ofcurvature of 250 to 500 mm is suitable. In the illustrated embodimentthe radius of curvature is 375 mm.

Whilst the invention has been described particularly with reference tocontainers in the form of dump bodies on dump trucks, it will beappreciated that the invention is not limited thereto and is applicableto any material transport container is which the material is unloaded byflowing out of the container, such as buckets in front end loaders andthe like.

1. A dump truck body having a floor and two opposed side walls and afront wall, said walls extending upwardly from the floor, the bodyfurther having an unloading end, the body being supported to enabletilting for unloading of material from the unloading end, the bodycomprising a plurality of hard faced wear plates providing asubstantially continuous and smooth hard faced sliding surface on anunloading portion of the floor adjacent the unloading end, so as toenhance the sliding of material over the smooth hard faced slidingsurface, the wear plates comprising a layer of hard surfacing alloy,over a mild steel base, a surface of the alloy finished to form the hardfaced sliding surface, there being provided one or more curved, arcuatesurfaces bridging a junction between one or more of the front and sidewalls and the floor of the body to reduce hangup of material thereon. 2.A dump truck body as in claim 1 wherein the one or more curved, arcuatesurfaces comprise one or more arcuate hard faced wear plates each havinga layer of hard surfacing alloy over a mild steel base, a surface of thealloy of the arcuate wear plate being finished to form an arcuate smoothhard faced surface.
 3. A dump truck body as in claim 2 wherein one ofthe one or more curved, arcuate surfaces bridges a junction between thefront wall and the floor of the body.
 4. A dump truck body as in claim 2wherein one of the one or more curved, arcuate surfaces bridges ajunction between the front wall and the floor of the body, and two otherones of said one or more curved, arcuate surfaces bridge joints betweenthe opposed side walls and the floor on either side of the unloadingportion of the floor.
 5. A dump truck body as in claim 2 wherein one ofthe one or more curved, arcuate surfaces bridges a junction between thefront wall and the floor of the body, and two other ones of said curved,arcuate surfaces bridge joints between the opposed side walls and thefloor on either side of the floor, and extending along the length of thefloor.
 6. A dump truck body as in claim 1 wherein the smooth hard facedsliding surface is provided by a liner fastened to the dump truck body.7. A dump truck body as in claim 6 wherein the liner is provided by aplurality of said wear plates.
 8. A dump truck body as in claim 7wherein said wear plates are spaced apart to allow for flexion betweenadjacent ones of said wear plates.
 9. A dump truck body as in claim 7wherein a gap between adjacent ones of said wear plates is less than 20%of a width of the adjacent ones of said wear plates.
 10. A dump truckbody as in claim 9 wherein the gap is about 25 mm.
 11. A dump truck bodyas in claim 2 wherein a radius of the one or more curved, arcuatesurfaces is greater than about 250 mm.
 12. A dump truck body as in claim2 wherein a minimum radius of the one or more curved, arcuate surfacesis about 300 mm.
 13. A dump truck body as in claim 6 wherein the mildsteel base is between 5 and 11 mm in thickness.
 14. A dump truck body asin claim 1 wherein the hard surfacing alloy is a carbide containingalloy, with primary and secondary carbides in an alloy matrix.
 15. Adump truck body as in claim 1 wherein the hard faced sliding surface hasa Brinell hardness of
 500. 16. A dump truck body as in claim 13 whereinthe thickness of the alloy is between 6 and 12 mm.
 17. A dump truck bodyas in claim 2 wherein the arcuate surfaces are provided by a linerfastened to the body.
 18. A dump truck body as in claim 1 wherein saidone or more curved, arcuate surfaces are provided by a liner fastened tothe dump truck body.
 19. A dump truck body as in claim 1 wherein theunloading portion of the floor with a hard faced surface is about 0.5meters taken from the unloading end of the floor.
 20. A dump truck bodyas in claim 1 wherein the unloading portion of the floor with a hardfaced surface is about 1 meter taken from the unloading end of thefloor.
 21. A dump truck body as in claim 1 wherein the unloading portionof the floor with a hard faced surface is about one third of the floortaken from the unloading end of the body.